HonkIOReference
Rate limits
Each account can make 100 API requests per second across all of its keys. Every authenticated response says how much of the limit is left.
Rate limits
Each account can make 100 API requests per second, across all of its keys, test and live alike. Every authenticated response carries X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset (Unix seconds). A request over the limit is refused with 429 RATE_LIMITED and Retry-After: 1, and nothing is charged for it.
Sending has its own limits on top of this, such as a daily cap and a per-recipient rate: see SMS sending limits and email limits.